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<H1>IBM Visualization Data Explorer Programmer&#39;s Reference</H1>
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<H3><A NAME="HDRDXQCA"
HREF="progu097.htm#PToC_370">DXQueryConstantArray</A></H3>
<A NAME="IDX1973"></A>
<A NAME="IDX1974"></A>
<P><STRONG>Function</STRONG>
<P>
Determines whether an Array contains constant data, and, if so,
returns both the number of items and in the array and the data value.
<P><STRONG>Syntax</STRONG>
<BR>
<TT><STRONG><BR>
&#35;include &lt;dx/dx.h&gt;<BR>
<P><BR>
Array DXQueryConstantArray (Array a, int *num, Pointer data)<BR>
</STRONG></TT><BR>
<P><STRONG>Functional Details</STRONG>
<P>
<TT><STRONG>
DXQueryConstantArray
</STRONG></TT>
determines if Array
<TT><STRONG>
a
</STRONG></TT>
contains constant data.  If so, if
<TT><STRONG>
num
</STRONG></TT>
is not <TT><STRONG>NULL</STRONG></TT>, the number of items contained in
<TT><STRONG>
a
</STRONG></TT>
is returned in
<TT><STRONG>*num</STRONG></TT>.  If
<TT><STRONG>
data
</STRONG></TT>
is not <TT><STRONG>NULL</STRONG></TT>,
the constant value contained in
<TT><STRONG>a</STRONG></TT> will be copied to the block of memory pointed to
by <TT><STRONG>data</STRONG></TT>.  In this case
<TT><STRONG>data</STRONG></TT>
should point to a block of memory
large enough to hold one element of
<TT><STRONG>a</STRONG></TT>; this size can be determined by calling
<TT><STRONG>DXGetItemSize(a)</STRONG></TT>.
<P>
<TT><STRONG>DXQueryConstantArray</STRONG></TT> considers both Constant
Array and Regular Array Objects with zero delta values to be constant.
<P>
The value stored in <TT><STRONG>a</STRONG></TT> may also be accessed by
a call to
<TT><STRONG>DXGetConstantArrayData</STRONG></TT>.
This call returns a pointer to the internal memory of
<TT><STRONG>a</STRONG></TT>, providing a <I>read-only</I> copy of the
data without the need to allocate a block of memory.
<P><STRONG>Return Value</STRONG>
<P>
Returns <TT><STRONG>a</STRONG></TT> if <TT><STRONG>a</STRONG></TT> contains
constant
data or <TT><STRONG>NULL</STRONG></TT> (without setting an error code)
if <TT><STRONG>a</STRONG></TT> is an Array that does not contain
constant data;
otherwise, returns <TT><STRONG>NULL</STRONG></TT> and sets an error code.
<P><STRONG>See Also</STRONG>
<P>
<TT><STRONG>
<A HREF="progu165.htm#HDRDXGCAD">DXGetConstantArrayData</A>,
<A HREF="progu180.htm#HDRDXGIS">DXGetItemSize</A>,
<A HREF="progu249.htm#HDRDXNCAV">DXNewConstantArray, DXNewConstantArrayV</A>,
<A HREF="progu259.htm#HDRDXNRA">DXNewRegularArray</A>
</STRONG></TT>
<P>
<A HREF="progu046.htm#HDRCTAS">"Constant Arrays"</A>.
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